Needles syringes or hypodermic syringes as they are more commonly termed are commonly employed for injecting fluids into both humans and animals. Such hypodermic syringes commonly include a barrel or body for containing the fluid to be injected. A plunger is usually operable at one end of the barrel for forcing the fluid from the barrel through a needle which is commonly mounted by means of a needle hub at the other end of the barrel. The preceding description of a hypodermic syringe is set forth herein only as an example and is not intended to be limiting in terms of the present invention.
Syringes of the type described above are widely used by health professionals such as doctors, nurses, lab technicians, hospital staff and others providing treatment particularly for human patients.
However, regardless of the particular application for the syringe, it has become important to protect the health professionals and others during the manipulation of hypodermic syringes, intravenous needles and the like, for example, to administer medication and/or to aspirate blood or other body fluids. Such protection is particularly essential after the syringe has been used either for injection or aspiration in order to assure that the needle does not penetrate any body portion of the operator. So-called "needle sticks" have proven to be particularly serious where the syringe has been employed on a patient having an infectious disease.
In such situations, the syringe has been known to slip from an operator's hand with its possibly contaminated needle penetrating part of the operator's body such as a leg, foot or hand. The most common form of "needle stick" injury is in recapping the needle with a standard cap after use of the syringe. Various shield assemblies have been employed in the past for minimizing or eliminating such accidents. Usually, it is necessary for the operator to position the shield or allow the shield to automatically assume a position for shielding the needle from subsequent contact. Typical prior art examples of such shield devices are discussed in greater detail below.
For example, U.S. Pat. No. 4,631,057, issued Dec. 23, 1986 to Mitchell disclosed such an apparatus having two relatively movable cylinders for engaging a syringe barrel to provide such a shielding function. U.S. Pat. No. 4,897,083, issued Jan. 30, 1990 to Martell disclosed yet another syringe needle guard including multiple cylinders telescopically arranged for extension and retraction to accomplish a similar purpose.
U.S. Pat. No. 3,658,061, issued Apr. 25, 1972 to Hall and U.S. Pat. No. 4,664,259, issued May 12, 1987 to Landis both provided needle guard units including hinged shield components or covers capable of being swung into protective relation with a needle.
U.S. Pat. No. 4,927,018 issued May 22, 1990 to Yang, et al. disclosed yet another needle assembly and cylindrical cover housing which is believed to be representative of a number of similar prior art references wherein a syringe or a portion of the syringe such as a needle hub requires modification for use of the syringe with the shield assembly.
U.S. Pat. No. 4,976,702, issued Dec. 11, 1990 to Andrews, et al. also disclosed a syringe needle guard or shield adapted for mounting on a hub by which the needle was secured to a syringe. U.S. Pat. No. 4,373,526, issued Feb. 15, 1983 to Kling disclosed a sheath assembly for an injection wherein the sheath was configured to apply pressure to the skin during injection for one or more desired purposes.
Additional references disclosing such devices include, for example, U.S. Pat. No. 4,356,822, issued Nov. 2, 1982 to Winstead-Hall; U.S. Pat. No. 4,738,663, issued Apr. 19, 1988 to Bogan and U.S. Pat. No. 4,900,309, issued Feb. 13, 1990 to Netherton, et al. It is noted once again that all or most of the above references are representative of additional prior art relating to such protective shields or devices. In any event, these devices have been found generally satisfactory for their intended purpose. At the same time, there has been found an obvious need for further improvements in such protective devices, for example, either to simplify or improve use of the syringes while protecting those handling the syringes or capable of coming into contact with them.